The present invention relates to a method for fabricating a semiconductor device, and more particularly, to a method for fabricating a storage node contact plug in a semiconductor device.
A contact is generally required to have a certain size or less in order to maintain an overlap margin with a landing plug isolation layer, i.e., an under layer, when forming a storage node contact plug. The size of an upper portion of the storage node contact plug is usually required to be larger than a certain level in order to secure an overlap margin with a subsequent storage node, and to secure a desired contact resistance. Accordingly, an additional plug pad process has been performed on an insulation layer such that the storage node contact plug and the storage node may improve the above difficulty. However, the additional plug pad process causes an increased number of processes and increased development costs, decreasing the throughput.
Furthermore, when the size of a storage node contact mask is increased to maintain the size of the upper portion of the storage node contact plug, a bridge may be generated between adjacent storage node contact plugs because of a lack of margin between storage node contact holes after performing an etching process to form the storage node contact holes.
Also, the increased size of the storage node contact plug may cause a lack of margin with the landing plug isolation layer, i.e., the under layer. Accordingly, an etch loss may be generated on the landing plug isolation layer during the etching process for forming the storage node contact holes (refer to ‘A’ shown in FIG. 1).